Forming apparatus for profile grinding wheels



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May 16, 1961 Filed Feb. 18', 1959 H. s. HALLEWELL 2,984,233

FORMING APPARATUS FOR PROFILE GRINDING WHEELS 3 Sheets-Sheet 1 ye/woe H. 5. HALLEWELL A 0 NE) FORMING APPARATUS FOR PROFILE GRINDING WHEELS Filed Feb. 18, 1959 May 16, 1961 H. s. HALLEWELL 5 Sheets-Sheet 2 6, 1961 H. s. HALLEWELL 2,984,233

FORMING APPARATUS FOR PROFILE GRINDING WHEELS Filed Feb. 18, 1959 5 Sheets-Sheet 3 W WX United States Patent FORMING APPARATUS FOR PROFILE GRINDING WHEELS Harold Stuart Hallewell, Connaught Works, Uxbridge Road, Hillingdon Heath, England Filed Feb. 18, 1959, Ser. No. 794,105

Claims priority, application Great Britain Apr. 2, 1958 7 Claims. (Cl. 125-11) This invention relates to forming apparatus for profile grinding wheels, viz. apparatus for the formation or trueing on a grinding wheel of a profile that is required to be imparted by the grinding wheel to a tool, die, gauge or other workpiece.

The apparatus to which the invention relates comprises a tool carrier adapted to carry two or more forming tools intended to be used selectively for difierent degrees of forming or trueing, e.g. for coarse and fine forming of the grinding wheel profile. In use, the apparatus is appropriately mounted relative to the grinding machine and the tools are capable of adjustment so as to enable them to be brought selectively into the appropriate position for engagement with the periphery of the grinding wheel. For the said selective adjustment, the tools are movable together in a direction at right angles to the grinding wheel axis, and for the purpose of imparting the required profile to the grinding wheel they are also movable angularly about an axis parallel to the said direction.

For example, the tool carrier may form the follower member of a pantograph mechanism which includes a tracer member adapted to follow the profile of a template, the follower member being arranged to reproduce, generally on a smaller scale, the profile traced out by the tracer member as it follows the profile of the template.

The follower member and the tracer member of such a pantograph mechanism are capable of executing, independently of the setting of the pantograph mechanism, angular movements about axes that are at right angles to the general plane of the pantograph mechanism and are interconnected eg by a linkage so that angular movements of the tracer member about its axis result in similar angular movements of the follower member. The tools must be capable of adjustment in a direction at right angles to the general plane of the pantograph, so as to enable the forming tools to be brought selectively into the appropriate position for engagement with the periphery of the grinding wheel.

A very high degree of precision is necessary in the various pivot points of the pantograph mechanism and in the bearings that permit the above-mentioned angular movements of the tracer and follower members. The follower member is mounted in high precision bearings at an appropriate part of the pantograph mechanism, for the purpose of permitting its said angular movement. A degree of inprecision is however introduced by the need to allow for movement of the tools in a direction at right angles to the plane of the pantograph mechanism and therefore the need for the follower member itself to be capable of such movement in addition to its angular movement.

The object of the invention is to overcome or reduce this disadvantage, which arises not only where the tool carrier is the follower member of a pantograph mechanism, but also quite generally where the tools require to be adjustable in one direction to permit their selective use and also to be angularly movable about an axis parallel to the said direction.

Patented May 16, 1961 In accordance with the invention the tool carrier includes two main parts, viz. one part journalled in a mounting for angular movement about an axis but substantially incapable of movement in the direction of said axis, and the second part being a tool holder connected to the said first part so as to be substantially incapable of angular movement relative to said first part but capable of adjustment relative thereto in a direction parallel to the said axis.

In order that the invention may be clearly understood and readily carried into effect it will now be described in more detail with reference to the accompanying drawings, in which Fig. l is a plan view of part of a grinding machine embodying the invention, in which the mounting in which the said first part of the tool carrier is journalled is an arm of a pantograph mechanism,

Fig. 2 is a side view of the machine shown in Fig. 1, and

Fig. 3 is a view of the follower member in sectional elevation, on a larger scale than Figs. 1 and 2.

Referring to the drawings, the grinding machine includes a grinding Wheel 1, a template 2, and pantograph mechanism for forming or trueing the profile of the grinding wheel 1 in accordance with the shape of the template 2. The pantograph mechanism comprises a front link 3 and a rear link 4 arranged parallel to one another in a horizontal plane and two side links 5 and 6 also arranged parallel to one another and pivotally connected to the front and rear links to form a parallelogram linkage system. The pivot connection 7 between the links 4 and 6 is mounted on the top of a carriage 8 which is slidable in directions transverse to the axis of the grinding wheel, which is carried by a fixed part of the machine. The side link 5 extends beyond the rear link 4, and a tracer member is mounted in a bearing housing 9 on the free end of the side link 5 for rocking movement about a vertical axis, the tracer member comprising a handle 10 above the housing 9 and a stylus 11 projecting downwards through and below the housing 9 and aligned with the rocking axis of the tracer member. The stylus is capable of bearing against the profiled edge 12 of the template 2. The front link 3 extends beyond the side link 6, and a follower member is mounted in a bearing housing 13 on the free end of link 4 for rocking movement about a vertical axis.

The follower member, which will be described hereinafter in more detail, is coupled to the tracer member by a rod 14 one end of which is pivotally connected to the tool carrier or follower member and the other end of which is pivotally connected to one arm of a bell crank 15 angularly movable on the pivot between the links 3 and 5, and by a further rod 16 one end of which is pivotally connected to the tracer member and the other end of which is pivotally connected to the other arm of the bell crank 15. The rods 14 and 16 thus constrain the tracer and follower members to rock in unison upon angular movement of the handle it Since the tracer and follower members are arranged on opposite sides of the fixed pivot 7, the pantograph mechan i sm operates in reverse, so that movement of the tracer member say to the right in Figs. 1 and 2 imparts movement of the follower member to the left and so on. Therefore, when the stylus 11 is caused to follow the profiled edge 12 of the template 2 the axis of the follower member will execute a path which is the reverse of the said profile but reduced in accordance with the magnification factor of the pantograph mechanism.

Referring now to Fig. 3, the'tool carrier or follower member comprises a first main part in the form of a spindle 17 with its axis vertical, journalled at each end in precision bearings in the front link 3 of the pantograph mechanism, so as to be capable of movement about its axis; Suitable means including discs 18 cooperating with shoulders on the spindle are provided for preventing axial movement of the spindle 17 relative to the link 3. The spindle 17 is coupled by the rods 14 and 16 and bell crank to the tracer member so as to execute angular movements in unison therewith. The lower end of spindle 17 carries a horizontal plate 20 to which is fixed a support 21 which has a flat horizontal upper surface which is in contact with the fiat lower surface of the plate 20. The support 21 is fixed to the plate 20 so as to be incapable of movement relative to it, and projects horizontally away from the front link 3 and side link 6, and the projecting portion of the carrier 21 is formed with two vertical cylindrical bores in each of which are disposed respectively cylindrical slides 22 and 23 which are close sliding fits in their bores and can slide vertically therein. The slides 22 and 23 project downwardly from the support 21 and are both firmly secured in the upper part of a tool holder 24, the slides 22 and 23 and the tool holder 24 forming the second main part of the follower member. Vertical adjustment of the slides 22 and 23 and therefore of the tool holder 24 is effected through the intermediary of a pinion 25 which is rotatable by means of a handle (not shown) and which is in toothed engagement with a rack 26 on the slide 23. For fixing the tool holder 24 in the required vertical position, there is provided a wedge 27 which is carried by support 21 and is operable to exert a wedging action on the slides 22 and 23 and force them against the sides of the bores in the support 21. The tool holder 24 carries two forming tools 28 and 29 which are adjustable in the holder 24 and are readily removable therefrom, the tools being mounted one above the other in the holder 24 with their working edges facing the grinding wheel. ()ne of the tools 28 and 29 is intended for coarse forming of the grinding wheel and the other tool is intended for fine forming.

When the tool holder 24 is correctly vertically adjusted to bring the required tool 28 and 29 to an operative position, the working edge of the said tool is substantially in a horizontal plane through the axis of the grinding wheel, the inoperative tool being above or below this plane. The invention enables the vertical setting of the tools and their selection to be effected independently of the spindle 17 by suitable vertical adjustment of the slides 22 and 23 in the support 21, the tools nevertheless moving angularly about the vertical axis of the spindle in unison therewith. The invention further enables a high degree of precision to be maintained in the bearings of the spindle 17 and in the vertical guiding of the tool holder 24.

A profile grinding machine need not necessarily incorporate a pantograph mechanism, and in another embodiment of the invention, the first part of the tool carrier is journalled in a fixed mounting instead of being journalled in the movable mounting constituted by an arm of a pantograph mechanism, and the second part of the tool carrier viz. the tool holder, is slidably connected to the first part for movement in a direction at right angles to the axis of angular movement of the first part. For example, the construction shown in Fig. 3 may be modified by replacing arm 3 by a fixed mounting and providing a sliding connection being the plate 20 and the carrier 21 so that the tool holder 24 can be moved (horizontally as seen in Fig. 3) away from, towards or beyond the axis of the spindle 17. The forming tools 28 and 29 will then always follow true arcuate paths centered on the axis of spindle 17, when the kob 30 is rotated.

I claim:

1. In apparatus for forming a profile on grinding wheels, a tool carrier comprising a first main part journalled in a mounting of the apparatus for angular movement about an axis, means preventing axial movement of the first main part relative to the mounting, a second main part, guide means on one of said parts and extending in a-direction parallel to the said axis, the other of said parts being slidably mounted on said guide means for movement in said direction, said guide means preventing angular movement of said other part relative to said one part, means for adjusting the position of said other part along guide means, and means on said second main part for simultaneously locating two tools thereon.

2. In apparatus for forming a profile on grinding wheels, a tool carrier as set forth in claim 1, wherein said guide means comprises two shafts secured to said one main part, and said other main part is provided with two cylindrical apertures, the two shafts being a close sliding fit within said apertures.

3. In apparatus for forming a profile ongrinding wheels, a tool carrier as set forth in claim 2, wherein the axes of said shafts and the first mentioned axis lie in a; common plane.

4. In apparatus for forming a profile on grinding wheels, a tool carrier as set forth in claim 3, wherein the said other main part includes wedge means disposed between said two shafts and operable to force said shafts in opposite directions and thereby clamp the said other part on the shafts.

5. In apparatus for forming a profile on grinding wheels, a pantograph mechanism, a tracer member and a follower member mounted on said pantograph mechanism for angular movement about axes that are perpendicular to the general plane of the pantograph mechanism, means interconnecting the tracer and follower members for effecting angular movement of the two members in unison, independently of the setting of the pantograph mechanism, the said follower member comprising a first main part journalled in a mounting on said mechanism, and a second main part, guide means on one of said main parts, said guide means extending in a direction perpendicular to the general plane of the pantograph mechanism, the other of said main parts being slidably mounted on said guide means, means for adjusting the position of said other main part for simultaneously locating two tools thereon at different distances from the general plane of said pantograph mechanism.

6. In apparatus for forming a profile on grinding wheels, a pantograph mechanism, a tracer member and a follower member mounted on said pantograph mechanism for angular movement about axes that are perpendicular to the general plane of the pantograph mechanism, means interconnecting the tracer and follower members for effecting angular movement of the two members in unison, independently of the setting of the pantograph mechanism, said follower member having two cylindrical apertures arranged parallel to the pivot axis of the follower member, a tool holder having two shafts slidably mounted in said apertures, means for adjusting the position of the tool holder relative to the follower member, and means on said tool holder for simultaneously locating two tools thereon at different distances from the general plane of the said pantograph mechanism.

7. In apparatus for forming a profile on grinding wheels, a pantograph mechanism, a tracer member and a follower member mounted on said pantograph mechanism for angular movement about axes that are perpendicular to the general plane of the pantograph mechanism, means interconnecting the tracer and follower members for effecting angular movement of the two members in unison, independently of the setting of the pantograph mechanism, said follower member having two cylindrical apertures arranged parallel to the pivot axis of the follower member, the axes of said apertures and the said pivot axis lying in a common plane, a tool holder having two shafts slidably mounted in said apertures, one of said shafts being provided with teeth and constituting a toothed rack, a toothed pinion rotatably mounted in said follower member and meshing with said toothed rack, the pinion and rack serving to adjust the position of the tool holder relative to the follower member, wedge means disposed between the two cylindrical apertures in the follower member and operative to force said shafts in opposite directions and thereby clamp the tool holder to the follower member, and means on the tool holder for simultaneously locating two tools thereon at different distances from the general plane of said pantograph mechanism.

References Cited in the file of this patent UNITED STATES PATENTS Cooke Mar. 11, 1941 Hoaglancl Oct. 18, 1955 FOREIGN PATENTS Great Britain Apr. 22, 1953 

